RESUMEN
BACKGROUND: The structural changes of the respiratory system related to ageing determine lung function decline in healthy subjects after 25 years of age. An annual reduction of 25 ml in Forced Expiratory Volume in 1 s (FEV1) is expected. We aimed to describe the longitudinal lung function variation of subjects with severe asthma receiving appropriate treatment. METHODS: Consecutive patients enrolled in a Brazilian reference clinic between 2003 and 2006 were invited to participate. The study participants were followed up for a median of 8 years, and were evaluated with spirometry in three distinct occasions (V0, V1 and V8), at least. At V0, upon enrollment, subjects with previous severe untreated asthma were evaluated by a specialist, had their health resource utilization in the last 12 months recorded, and performed spirometry. In V1, 1 year after V0, under proper management, subjects repeated the procedures and answered the Asthma Control Questionnaire (ACQ) and the Asthma Quality of Life Questionnaire (AQLQ). In the last study visit (V8), 7 years after V1, all patients underwent a pre and post-broncodilator (postBD) spirometry, skin prick test for aeroallergens, answered the ACQ and the AQLQ and had another interview with the specialist. RESULTS: Two hundred thirty-four subjects were followed up between V0 and V8. A comparison between spirometries of V1 and V8, after the initial improvement has supposedly reached a plateau, shows that the FEV1 and FVC declined significantly both in absolute and percent of predicted values. FEV1postBD did not change significantly between V0 and V1, but declined by -27.1 (-51.1-1.4) ml/yr between V1 and V8. CONCLUSIONS: Currently available treatment with a combination of inhaled corticosteroids and LABA may not be sufficient to prevent lung function decline in subjects with severe asthma.